What is moisture sorption isotherm in food?

What is moisture sorption isotherm in food?

The food sorption isotherm describes the thermodynamic relationship between water activity and the equilibrium of the moisture content of a food product at constant temperature and pressure.

How is water sorption isotherm related to the moisture content in a food?

Manometers determine water activity by directly measuring the vapor pressure above a food. The moisture sorption isotherm of a food is obtained from the equilibrium moisture contents determined at several water activity levels at constant temperature.

Does relative humidity have any effect on food texture?

The relative humidity impacts the quality and texture of baked goods.

What is moisture desorption?

For definition of the needed conditioning parameters, the moisture desorption properties were determined by measuring the desorption behavior. The measured sorption isotherms show the moisture load of the material in a state of equilibrium under constant temperature at different levels of relative humidity.

What is equilibrium humidity?

Equilibrium relative humidity (ERH) is the relative humidity of the atmosphere at a particular temperature at which a material neither gains nor loses moisture. Hygroscopic materials, by absorbing or desorbing moisture at a certain relative humidity of the ambient air, reach the ERH.

What is relative humidity vs humidity?

Humidity is the water content of the mixture of water vapor and other elements found in the air while relative humidity is the percentage of water vapor in the air at a given temperature.

How does humidity affect cooking?

Humidity is something that traditional ovens have no control over. Water molecules conduct heat much faster than air. Not only does humid air transfer heat more efficiently to food, cooking it more quickly, it also helps prevent the water in the food from evaporating, keeping the moisture locked inside.

Does humidity make food taste better?

Paul Breslin, a member of the Monell Chemical Senses Center and professor in the Department of Nutritional Sciences at Rutgers University, said that the loss of humidity and change in your sense of smell likely has a greater impact on the food’s flavor than the change to your sense of taste.

What are the types of moisture sorption isotherms for food?

Moisture sorption isotherms of most foods are nonlinear, generally sigmoidal in shape, and of the type II classification [ 1, 6 ]. Figure 1. Types of moisture sorption isotherm for food. Source: Rizvi [ 6 ].

What does a moisture sorption isotherm look like?

Some foods may give a moisture sorption isotherm more like the one below, in the shape of an S. (Keep in mind that the illustrations are extreme examples of products. Most foods will start with a horizontal line at lower water activities and will show this S-like behavior at higher values.)

How do you use sorption isotherms to predict shelf life?

Shelf Life Determination Sorption isotherms are valuable for shelf life prediction. They can be used to determine a food’s monolayer moisture content and the corresponding water activity, which represents its most stable state. The monolayer value is determined by modeling isotherm data using the GAB or BET equations.

What is the best model for moisture sorption?

Commonly used moisture sorption isotherm models (BET, GAB, modified GAB, Hailwood-Horrobin, modified Hailwood-Horrobin, modified Halsey, modified Henderson, modified Chung-Pfost and modified Oswin) were selected, and their evaluation procedures using moisture sorption data were outlined.

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